Exoplanet's Surprising Detour Reignites Astronomical Debate

By Veronique Greenwood | September 27, 2011 1:09 pm

spacing is important
When Fomalhaut b was announced in 2008, images showed it following a clear orbit around its star.

What’s the News: Even if you don’t know an exoplanet from an exoskeleton, you probably saw the gorgeous images of Fomalhaut, aka “Sauron’s Eye,” making their way around the web in 2008. A tiny, bright dot in the star’s surrounding dust cloud had moved, showing itself to be a planet—the first planet beyond our solar system to actually be seen, rather than detected with nonoptical instruments. Cue the champagne!

But new pictures show something odd: Fomalhaut b, as the planet was named, is veering off in an unexpected direction. Does this mean it’s not a planet after all, or is there another explanation?

What’s the Context:

  • Fomalhaut b showed up in two different images taken by the Hubble Space Telescope in 2004 and 2006. In the intervening years, the object had moved, appearing to sweep out an orbit through the star’s dust cloud.
  • But Fomalhaut b is kind of weird, as exoplanets go. It’s very bright, way brighter than astronomers would expect from a planet that size, and it’s also not visible in the infrared spectrum in pictures taken from Earth, which is kind of fishy—astronomers think the planet is young, so it should burn bright in infrared, but it hasn’t shown up yet. The planet’s brightness, at least, astronomers think, might be from a layer of dust that’s accrued around it, like the rings around Saturn.
  • Additionally, its status as the “first directly observed” exoplanet has ruffled some people’s feathers, in a scientific community where excitement about new planets has reached a fever pitch. Ray Jayawardhana, an astronomer at University of Toronto, says that if dust is behind the brightness, technically speaking it’s not the planet that’s been directly observed. “They continue to call it a directly imaged planet,” he told Eric Hand of Nature News. “I think it’s time to stop doing that.”

Not a Planet?

  • Now, a new observation taken in 2010 and presented by Paul Kalas of UC Berkeley at a recent conference shows that the planet isn’t continuing along what scientists thought was its path. It looks like it’s continuing on into the dust instead.
  • Jayawadhana takes that as an indication that it may not be a real planet, he tells Nature News, which has a fascinating rundown of the science—and scientific politics—involved.
  • Fomalhaut b’s clear orbit, which appeared to have cut a path through the star’s dust cloud over the eons, was one of the reasons astronomers dubbed it a planet. Although it’s possible that the orbit just happens to have some instability built in, if the object takes a substantial detour, that is a potentially serious strike against planethood.

Not So Fast:

  • The new image was taken with a different camera than the one that recorded Fomalhaut b in 2004 and 2006, Kalas notes. The high-resolution channel Kalas and company used then was not replaced when the Advanced Camera for Surveys broke, so the new image is taken with the Space Telescope Imaging Spectrograph.
  • That difference in instrumentation, for now, means that it’s possible that Fomalhaut B’s veer is just an artifact.

The Future Holds: Kalas is going to get another chance to snap a picture of the planet next summer. That should help resolve whether this anomalous movement is real—and thus give greater insight into Fomalhaut B’s celestial status.

[via Nature News]

Image courtesy of ESA, NASA, and Paul Kalas

  • Bean Soup

    Large Borg spacecraft?

  • Liath

    Obviously what we have here is a gigantic spaceship carrying the entire population of their home planet that they had just finished trashing. Perhaps we should consider a similar space bound project.

  • nephelegereta

    Could still be a planet, but a rogue one, which would explain anomalous IR signal – not as young as they thought, but still reflective because of accrued dust.
    @ Bean Soup – couldn’t be Borg, isn’t square 😉

  • M Tadano

    Well… there are people who obviously like to “demote” planets to something else. Just ask Pluto! :-)

  • http://bossy-girls.net Lila Sovietskaya

    When I read the article, the same weird idea commented by Bean Soup and Liath. So I was amazed to see other people with weird idea as mine. The truth might be some malfunction in the instrumentation taking the data, or the exoplanet might be falling into a gravitational distortion of some other unseen wandering object. has the stardust affected the path? That is a very likely explanation that could be examined.

  • Chrysoprace

    Has this system been analyzed with other means of planet detection? I am certainly no expert but couldnt an object have an erretic orbit if there were another very large body acting on it, say a triple Jupiter mass gas giant?

  • Caleb

    I’m with Bean Soup & Liath on this one.. hmmm.. although, why would such a large and advanced spacecraft allow itself to be so visible. So logic leads me to believe that this is a “triple Jupiter mass” gas giant transporting Borg.

  • http://www.branchout.com/LisetteRoot Simplylisette

    Perhaps the body itself is an eccentric shape with a lopsided center of gravity, or there is a sneaky little black hole nearby:)

  • Ernest

    @nephelegereta Don’t think it could be a rogue planet. Pictures suggest it’s orbiting the star. I’s more likely a glitch in the instrument or something else affecting the planet’s orbit.
    Could still be a borg ship, they also have spheres.

  • nephelegereta

    @Ernest – the Borg Queen out for a cruise? Ever since Jean-Luc left, she’s not been the same..assimilation has lost its joy :)

  • torres

    Not exactly the topic, but my curiosity has me asking: How would scientists differentiate between an exoplanet and an exocomet? We have planets in our solar system and comets, such as Halley’s, that both orbit the Sun.

  • John Kwok

    @ nephelegereta –

    Didn’t the Borg Queen have a date with Captain Janeway?

    On a more serious note, the nationally syndicated radio talk show hosted by John Batchelor had an excellent discussion on this which aired either last night or the night before. You can listen here:


  • PapaV

    If it is a Borg spacecraft and it comes here and assimilates me, I hope I get to meet Seven in person. :-)

  • John Kwok

    @ PapaV –

    You have a much better chance of meeting Seven if the USS Voyager uses the Kirk slingshot effect and travels backward in time!

    I have a hunch, however, that the Borg starship might really be either one of the Shadows or the Vorlons!

  • Geack

    Geez, what a bunch of geeks. It’s nice to be among my own kind 😉


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